Low oil pressure sensitive engine governor



April 6, 1965 M. R. ROWE ETAL LOW OIL PRESSURE SENSITIVE ENGINE GOVERNOR 4 Sheets-Sheet 1 Filed Nov. 2, 1961 INVENTORS MARK R. ROWE HARRY ATTORNEY April 6, 1965 M. R. ROWE ETAL LOW OIL PRESSURE SENSITIVE ENGINE GOVERNOR Filed Nov. 2, 1961 4 Sheets-Sheet 2 I u I I09 To Bellows l' [:1 -ll ||4 '20 I 96 I08 I07 "2 u MA HI] l A I I22 21 I13 I 8 I09 /-/oo l y I e j I A82 6 l i i I 1 58 I I I [IVE/NE DRIVEN ATTORNEY A ril 6, 1965 M. R. ROWE ETAL 3,176,672

LOW OIL PRESSURE SENSITIVE ENGINE GOVERNOR Filed Nov. 2. 1961 4 Sheets-Sheet a ave/m5 550 Reamer/mm OIL PBESSUEESUPPLY ENG/NE 5P E E D PEOPOE T/O/VA L O/L PEES'SUBE SUPPLY [IVE/NE DEA/[IV I i IIIIIII INVENTORS MA /?K A? ROWE HARRY C. ZE/SLOFT CLAUDE'B. Mc CATH/PO/V BY C) ATTORNEY A ril 6, 1965 M. R. ROWE ETAL 3,176,672

LOW OIL PRESSURE SENSITIVE ENGINE GOVERNOR PRESS INVENTORS MARK P. ROWE HARRY CZE/SLOFT CLAUDE B.Mc CATHRON RPM. (N) BY ATTORNEY United States Patent This invention relates to control devices for internal combustion engines in general and more particularly to low oil pressure sensing devices. It is also concerned with governors adapted to control the engine speed.

This invention is especially useful in internal combustion engine arrangements that receive lubricating oil under pressure from a pump, the output pressure of which increases in an approximately linear fashion as the speed of the engine increases. Such a relationship is commonly obtained from a conventional gear type pump driven by the engine.

It has been determined experimentally that increased lubricating oil pressure is required as the speed of the engine increases. Generally, the gear type pump supplies a sufliciently increased pressure as the speed of the engine increases. But it is not necessary that a pressure equivalent to the maximum pump output pressure be supplied to the engine bearings. It is only necessary that the pressure at a given speed bear a certain relationship to this output pressure.

As may be seen subsequently from thegraph forming a part of the specification, two relationships between the maximum pump output pressure and the safe operating pressure are feasible. The first relationship, considered to be the more desirable because of the greater diiferential provided at the higher speeds, contemplates a safe operating pressure that increases linearily as the speed of the engine increases, but having a more gradual increase than the maximum pump output pressure. Thus, at lower speeds the pressure differential is small whereas at higher speeds, it is large.

The second relationship establishes a safe operating pressure that also increases linearly as the speed of the engine increases; however, the increase in the safe operating pressure is at the same rate as the increase of the maximum pump output pressure. Thus, a constant pressure differential is permissible between the safe operating pressure and the maximum pump output pressure as the engine speed increases.

It is a primary purpose of this invention to provide an arrangement that is sensitive to a reduction in the pressure of the lubricating oil of an internal combustion engine below a predetermined safe operating pressure at any given engine speed. It is also a purpose of this invention to provide a signal to an operator or to automatically effect engine control when the lubricating oil pressure falls below a predetermined safe operating perssure at any given engine speed.

Also included within the scope of this invention is a new and novel arrangement of a governor adapted to regulate the maximum speed of an engine. A further object is to provide a governor wherein the operation is effected by the relationship between the'engine lubricating oil pressure and an engine speed sensing device. An additional object is to provide an arrangement that incorporates an engine overspeed governor with a low oil pressure sensing device.

In general, the arrangements that are disclosed herein to carry out the above objects of this invention include an engine speed sensing means positioned in relation to a lubricating oil pressure sensing means. 'Also included is a means responsive to the relative position of the engine speed sensing means and the lubricating oil pressure sensing means adapted-to, actuate engine control means or to signal an operator if the lubricating oil pressure falls below a predetermined safe operating pressure at any given engine speed. Other means also included to carry out the objects of this invention are adapted to prevent engine overspeed. In one form of this speed regulatory device a positive, travel-limiting means to arrest the movement of the lubricating oil pressure sensing means is utilized in conjunction with a speed sensing means to effect an unbalanced condition resulting in the actuation of the engine control means. In another form of this overspeed control arrangement an unbalance between the engine speed sensing means and the lubricating oil pressure sensing means to effect engine control is created by limiting the increase of the lubricating oil pressure within the lubricating oil pressure sensing means as the engine speed increases toward a maximum predetermined limit.

Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments, with reference being made to the accompanying drawings, wherein the same designations will be applied to elements that are substantially equivalent.

In the drawings:

FIGURE 1 is a sectional view of one embodiment of this invention;

FIGURE 2 is a sectional View of a second embodiment of this invention;

FIGURE 3 is a sectional view of a third embodiment of this invention;

FIGURE 4 is a cross sectional view of the third embodiment taken along line 44 of FIGURE 3;

FIGURE 5 is a sectional view of a further modification of the invention;

FIGURE 6 is a plan View of a preferred arrangement showing an engine control. or operator signaling device; and

FIGURE 7 is a line relationships.

In the embodiment shown in FIGURE' I, 14 designates a housing or casing having an upper chamber 15 and a lower chamber 16 adapted to receive the operative elements. Casing 14 is composed of sectional elements 17, 18 and 19 to form the chambers 15 and 16. V The congraph showing the oil pressure figuration of these-chambers is not essential to this invention; however, in the preferred embodiment they are cylindrical. Extending through the lower chamber 16 is a flexible diaphragm 21 retained within the housing by any suitable means. A cylindrical rod 23 is slidably mounted in a bore 22 formed in a partition 20 between the lower chamber 16 and the upper chamber 15, and has one end attached to the upper side of the diaphragm 21. To increase the bearing surface between the rod and the diaphragm, washers 24 and 255 are disposed between the rod 23 and an attaching nut 26 on opposite sides of the diaphragm. A non-linear spring 27 is disposed on the upper side of the diaphragm 21 with one end thereof adjoining the diaphragm and the other end seated around a flanged portion 23 extending from the center partition 20.

The upper chamber 15 contains a flexible diaphragm 29 also secured within the housing =14 by any suitable means. At the upper side of this diaphragm 29 a spool valve 31 is slidably mounted for movement in a bore 30 formed in the housing =14. The valve 31 is connected to the upper side of the diaphragm 29 by a nut 34 acting through washers 32. and 33 located on opposite sides of the diaphragm. A linear spring 35 is disposed within the chamber 15 with one end abutting the underside of the diaphragm 29 and the other end thereof resting on a support member 36 carried by the upper end of rod 23.

Pressurized oil, provided by a gear type oil pump in a conventional engine lubricating system, is supplied to the upper side of the lower diaphragm 21 through an inlet 37 and passages 38 and 39 in housing 14 while it reaches the upper side of diaphragm 29 through passages 38 and 40. An orifice 4-1 in passage 38 restricts flow to outlet passage 42. The outlet passage 42 may connect with a suitable oil conduit 43m convey oil to a pressure responsive device, such as a collapsible actuating bellows 44.. Passage 46 is provided within the housing 14 to provide a return to the engine oil sump and passage 47 connects the upper end of bore with passage 46 to prevent an oil leakage pressure build-up on the upper side of valve 31. Passage 43 connects the lower side of diaphragm 29 with the sump passage 46 to maintain the lower side of this diaphragm at substantially atmospheric pressure.

Disposed within housing 14 is a pump 49 having an impeller 56 which receives pressurized lubricating oil from inlet 37 through a passage 51 and further increases the oil pressure prior to its application to the lower side of diaphragm 21 through passages 52, 53 and 54. A shaft 55 driven by suitable means at a speed proportional to that of the engine rotates the impeller 50. It is not essential that any particular speed ratio be selected; however, it is desirable that the rotational speed of the impeller be sufiicient to raise the pressure ofrthe oil applied to the lower side of the diaphragm 21 to a level higher than the lubricating oil pressure at inlet 37. A conventional 0 ring 56 is provided to sealingly engage a journal 57 rotatably supporting the pump shaft within an extension 58 of housing 14. Relief passage 59 connects chamber 16 to the sump passage 46 to permit adequate circulation and cooling of the oil which has a tendency to be heated by the rotating impeller 50.

In this arrangement overspeed control is eiiected by limiting the maximum pressure on the upper side of the diaphragms 21 and 29. A piston 61 is slidably mounted in a bore 62 that is connected by a passage 66 with the upper side of diaphragm 29. A calibrated spring 63 biases piston 61 relative to a passage 64 so that the pressure applied on the upper side of diaphragm 29 can be regulated. An adjusting screw 55 can be provided to adjust spring 63 as desired.

In the embodiment shown in FIGURE 2, shaft 55 drives member of a magnetic coupling proportional toengine speed. The driving member 86 is formed to provide a base portion 31 and an upwardly extending flange 82. A ring-shaped permanent magnet 83 is supported on the base portion 81 and is spaced from the flange 32; however, it is not essential to this invention that a permanent magnet be utilized, Other devices, such as an electromagnet suitably energized through slip rings on the shaft 55, may be used.

A cup-shaped driven member 34 is placed in an inverted position between the permanent magnet 83 and the flange 82 of the driving member 86. In a conventional magnetic coupling of this character it is desirable to use a magnetic steel. for the flanges 82 to provide a path for the magnetic field of the magnet 83. It is also preferable to constitute the surfaces of cup-shaped member 84 extending into the magnetic fieldof copper so that the magnetic field can rotate member 84.

At its center the driven member 84 is rigidly connected to a vertical shaft 85 having one end 86 rotatably supported on the driving member as'at 87. An upper support for the shaft 85 is provided by a transversely extending supporting wall 88 having a central aperture 89 to receive the shaft.

Rotational displacement of the driven member is limited by a linear, fiat, spiral spring 99 loosely mounted around the shaft 85 connected at one'end to a stud 91 extending upwardly from the driven member 84 and at the other end to a stud 92 extending downwardly from the supporting wall 88. A cam 93 is affixed to. the upper end of the chamber 97.

1. shaftt85, as by a pin 94, to reflect the rotational movement of the driven member 84, thus positioning pin 95 extending downwardly from a sleeve 96 reciprocably fitted within a cylindrical chamber 97. A slot 98 in a wall 99 separating a lower chamber 10% and the chamber 97 permits horizontal movement of the pin 95. The cam 93 is proportioned to result in a predetermined horizontal movement of the pin 95 in response to a given increase in the angular rotation of the driven member 84 so that as the speed of the engine increases, the "sleeve 96 is positioned in linear relation to the speed.

A piston 1111 is also slidably mounted within the closely engaging the walls of the chamber and adapted to receive pressurized lubricating oil from inlet passage and passage 1%, a body portion 1113 slidably mounted within the bore of the sleeve 96, and a shoulder portion 194 formed at the junction of the head portion 10 2 and the body portion 1113. Two springs, 107 and 1118, seated against the end 189 of the chamber 97 serve respectively to bias piston 11)]; to a normal position and to hold sleeve 96 in a normal position wherein the pin 95 is held against cam 93.

A transversely extending passage 109 having a restrict- I ing orifice 11G connects passage 166 with a passage 111 to convey pressurized lubricating oil to an outlet port 112 and a bellows 44 adapted to be joined to an engine control arrangement similar to that shown in FIGURE 6. It also conducts pressurized lubricating oil to an enlarged cylindrical portion 113 of the chamber 97 encircling the sleeve 96 and a hole 114 provided through the sleeve. A return to the engine sump is provided through a passage 115 extending between the end 109 ofchamber 97 andthe extension 58 of the housing.

An additionalpassage 117 having a radially extending portion 118 and an axially extending portion 119 is provided within the body portion 103 of the piston 102 to relieve any accumulation of oil in the space 120 between tlge end 121 of sleeve 96 and shoulder 104 of the piston 1 1. t

The overspeed arrangement included in this embodiment utilizes a vertically extending pin 122, fixed at a predetermined point in the separating wall 99, that extends into the chamber 97 sufiiciently to engage the shoulder 1194 of the piston 101. As the latter moves to the right, as shown in the drawings, the travel of the piston is arrested when the shoulder 104 strikes the pin 122.

The embodiment shown in FIGURES 3 and 4 utilizes elements that are similar in many respects to the arrangements shown in FIGURES 1 and 2; thus, it can be seen that a centrifugal pump 49 having an impeller 50' receives pressurized lubricating oil from the engine lubrieating system through an inlet 37; increases the pressure gf the oil; and directs'it to the lower side of a diaphragm Pressurized engine lubricating oil is also supplied to an inlet 165 and through a passage 196 to a piston 101 slidably positioned in a chamber 97. As in FIGURE 2, a sleeve 96 biased by a spring 1138 receives body portion 193 of piston 101 that is biased by a spring 107.

It will be noted that pressurized lubricating oil is supplied to the upper side of diaphragm 21 through a passage 152 extending from end 153 of the chamber 97. The differential pressure between the upper side and the lower side of the diaphragm results in movement of the rod 23 against the resistance of the non-linear spring 27. A bell crank arrangement 149 pivoted about 147 is disposed in a chamber 159 between rod 23 and pin 95 which is afiixed to sleeve 96 to translate vertical movement of rod 23 to horizontal movement of sleeve 96. An arm engages the upper end of the control rod 23 and a forked arm 146 engages pin 95 to obtain this result.

The modification shown in FIGURE 5 illustrates a variation that may be adapted for use with the embodiments shown in FIGURES 1, 3 and 4. In this configura-.

It is comprised of a head portion 192 i tion, the upper side of the diaphragm 21 is connected through passage 156 to the sump return passage 115; thus maintaining this upper side of the diaphragm at substantially atmospheric pressure rather than at a pressure equal to the lubricating oil pressure as in FIGURES l, 3 and 4. It is necessary that a non-linear spring 157 be used having characteristics which result in linear movement of the rod 23 in response to the non-linear pressure supplied to the lower side of the diaphragm by the centrifugal pump 49. This requirement and relationship will be discussed in greater detail subsequently.

FIGURE 6 relates to a preferred arrangement adapted to eifectengine control or to provide a signal to an operator through engagement of a switch 294 placed in proper circuitry. Here, the pressure responsive device or bellows 44 carries a rod 2% supported in a journal 291. When in an extended position, the rod engages an arm 293 of a bell crank 262 to prevent the tendency of the bell crank to rotate clockwise due to the pull of spring 296 extending between the arm 2% and support 2tl7. If the bellows 44- collapses due to insufiicient pressure within, the rod moves to free the arm 2% permitting the arm 295 to be moved away from a contacting position with the switch 294.

A graph depicting the relationship between the various oil pressures of the control arrangements previously described is shown in FIGURE 7. Here the oil pressures in pounds per square inch are plotted against the revolutions per minute of the engine. It may be seen that the maximum lubricating oil pressure within the engine lubricating system, shown as line 220, increases in an approxi mately linear fashion as thespeed of the engine increases. This relationship may be obtained by the use of a con ventional gear type lubricating oil pump; however, the use of a gear type pump is not essential to the operation of this device.

Line 221 designates a preferred safe operating pressure for the lubricating oil as determined experimentally. It will be noted that this pressure level diverges from the maximum pressure within the system from a point where it is substantially equivalent to the maximum pressure at low engine speeds to a point where there is a wide permissible variation at high engine speeds.

In some installations it may be desirable to maintain a fixed differential between the maximum pressure of the system and the safe operating pressure. This relationship is shown by line 222. Such an arrangement requires closor control at higher engine speeds to provide adequate lubrication at lower speeds than the system wherein the safe operating pressure is shown by line 221.

The output pressure of the centrifugal pump 49 utilized in the embodiments shown in FIGURES l, 3 and 4 is de-- picted by line 223. It may be seen thatthe pressure increases in a non-linear fashion as the speed of the engine increases so that at higher engine speeds there is a greater divergence between the maximum lubricating oil pressure and this output pressure than at'lower speeds. It is not necessary that this centrifugal pump be of any given type, but it is desirable that it possess non-linear pressure characteristics, especially Where it is used in conjunction with an arrangement adapted to maintain the safe operating level of line 221. As will be subsequently discussed, non-linear characteristics are not essential to the modification shown by FIGURE 5.

Operation In the embodiment shown in FIGURE 1 pressurized lubricating oil is supplied to the inlet 37 and through passage 51 it is admitted to the impeller 54) of the centrifugal pump 49. The impeller is rotated by shaft at a speed proportional to that of the engine to increase the oil pressure in a non-linear fashion as shown by line 223 of FIGURE 7. This pressurized oil is applied to the lower side of the diaphragm 21 through passages 52, 53 and 54, thus providing a pressure that is controlled by engine speed and is independent of the lubricating oil pressure.

The lubricating oil, at inlet pressure, is supplied to the upper side of the diaphragm 21 from the inlet 37 upstream of impeller 51), through passages 33 and 39. Thus at any given engine speed there is dilference in pressure between the lower side and the upper side of the diaphragm 21 tending to move the diaphragm upward since the pressure on the lower side will be greater at any speed. The non-linear spring 27 counterbalances this differential. It is calibrated to give reduced deflection per pound of added force as the total applied force or pressure increases. As an illustration, if the pressure differential between the upper and lower sides of the diaphragm is five p.s.i. at 800 r.p.m., the spring may defiect /8" and if the pressure differential increases to 13 p.s.i. at 1600 r.p.m. it will deflect an additional 4;" in response to the added pressure of 8 p.s.i. These figures are merely illustrative and not indicative of actual values.

It can thus be seen that as the spring 27 is deflected, the

rod 23 is moved upwardly. Because of the non-linear characteristics of the spring 27, the non-linear variation of the pressure on the lower side of the diaphragm is resolved into linear movement of the rod 23. Assuming maximum lubricating oil pressure on the upper side of the diaphragm Zland proper compensating design of the spring 27, the rod 23 will be positioned at a point that reflects only engine speed.

Pressurized lubricating oil is supplied to the upper side of the diaphragm 29 in the upper chamber 15 through passages 38 and 49 extending from the oil inlet 37. The lower side of the diaphragm 29 is connected through passage 48 with the sump return passage 45. In the usual situation the pressure on this lower side of the diaphragm is at atmospheric pressure. Thus, the pressurized lubricating oil applied to the upper sideof the diaphragm 29 acts to move the diaphragm downwardly against the resistance of the linearly calibrated spring 35. This spring is calibrated so that every incremental increase in the pressure or force applied on the upper side of the diaphragm will move the diaphragm and the attached valve 31 downwardly a fixed distance at any given engine speed.

Assuming normal operating condition, this downward movement of the diaphragm 29 will equal the upward movement of the rod 23 and the platform 36 at any given speed, thus preventing the valve 31 from being positioned to expose passage 45 to the sump passage 46. It should be noted that in the inoperative state of this device, the lower diaphragm 21 is moved downwardly by the spring 27 carrying rod 23 and platform 36, and the diaphragm 29 is moved upwardly by spring 35 carrying the valve 31. Thus, in this inoperative condition, the net movement of the valve 31 is the same as under normal operat ing conditions and the passage 45 remains cut oil from the sump passage 46 by the valve.

The bellows 44 receives pressurized lubricating oil from the inlet passage 37 through passages 38, orifice 41, outlet 42 and connecting tube 43. In the preferred embodiment the pressure to the bellows must be maintained at 10 pounds per square inch to keep the bellows in an expanded position and to prevent the actuation of switch 204. Under normal operating conditions the pressure will build up to a pressure equivalent to that of the lubricrating oil which is above ten pounds per square inch. For example, it may approximate 49 p.s.i. at 4000 rpm. engine speed.

If for any reason the pressure of the lubricating oil falls below the maximum lubricating oil pressure at any given engine speed, the pressure on the upper side of the diaphragm 2% will fall and the spring 35 will move the diaphragm 29 and the valve 31 upwardly. At the same time, the pressure will be reduced on the upper side of the diaphragm 21 which will result in upward movement of the diaphragm 21, rod 23 and support 36. When the lubricating oil pressure falls below the point determined to 4 be a safe operating pressure, the resultant movement of the valve 31 will relieve the pressure at the bellows 44 by permitting drainage through passages 43, 42 and 45 to the sump passage 46.

It will be noted that a flow restricting orifice. 41 is provided in the passage 38 supplying lubricating oil to the bellows 44-. This results in more rapid and accurate response of the system to changes in lubricating oil pressure by restricting the amount of oil that may be supplied to the bellows when the valve 31 has been moved to expose passage 45 to passage 46. With no orifice present, if the valve 31 moved only slightly, high pressure oil flowing past it would tendto maintain the bellows pressure at p.s.i.

Referring to FIGURE 6, when the pressure of the lubricating oil has fallen below a safe operating pressure and the bellows .4 has collapsed, the rod 2% is moved out of engagement with bell crank 262.. This frees arm 203 of thebell crank 202, permitting spring 266 to pull arm 265 in a clockwise direction away from switch 2&4. The switch may have normally open or normally closed contacts to either make or break an electrical circuit associated therewith to effect engine control or .to provide a signal to an operator. In order to restart the engine this control unit would have to be reset in some conventional fashion. 7 I

As previously noted, it is desirable to maintain a diverging relationship between the maximum lubricating oil pressure and the safe operating pressure as the speed of the engine increases. To accomplish this the pressurized lubricating oil issupplicd to the upper side of the lower 'diaphragmll so that changes in this pressure are reflected in movement of the rod 23 as shown in FIGURE 1. However, the increment of movement of this rod is not directly proportional to the changes in pressure because of the non-linear characteristics of thespring 27.

As the speed at which the engine is operating increases,

the pressure differential between the upper and lower sides of the diaphragm 21 increases due to the divergence between the characteristics of the centrifugal pump output pressure andthe lubricating oil pressure as shown by lines 223and 220, respectively, of FIGURE 7. This differential pressure is resisted by spring 27 and at higher speeds, since the total forceappliedto the spring due to the higher differential pressure is greater, at one pound changein thispressure differential is resisted to a greater extent than a similar change at lower speeds. Consequently, the higher the speed, the lower the movement of the rod 23 in comparison to an equal reduction in the lubricating oil pressure at lower speeds. Conversely, at lower speeds, the greater the movement of the rod 23 in comparison to an equal reduction in the lubricating oil pressure at higher speeds.

With the rod 23 moving a smaller distance at higher speeds in response to lower lubricating oil pressure, the pressure drop, across diaphragm 29 must effect a greater movement of the diaphragm and the valve 31 to expose the bellows drain passages to the sump. To do this, it is necessary that the lubricating oil pressure fall a greater amount below the maximum lubricating oil pressure. It is apparent that this provides the desired relationship between the maximum lubricating oil pressure and the safe operating pressure as the engine speed is increased.

The overspeed control arrangement used with this embodiment of the invention limits the maximum allowable increase in the lubricating oil pressure applied to the upper side of the diaphragm 21 and the upper side of the diaphragm 29. This maximum pressure bears a relationship to the desired engine governing speed. Since this pressure is limited by the movement of piston 61 against the bias of the spring 62 to expose the upper side of the diaphragm 29 to the sump passage 4-6, the pressure supplied by the centrifugal pump 49 to the lower side of the diaphragm 21 and spring 35 pressing against the lower side of the diaphragm 29 act to move the valve 31 upwardly as the speed of the engine increases. At a predetermined increment of increase in the engine speed from tire point at which the piston moves to limit the pressure above the diaphragms 2i and 29 the valve 31 will be moved sufiiciently to expose the bellows passages to the sump passage. It will be noted that the speed at which the piston 60 moves to limit the maximum pressure is below the desired regulated speed by a predetermined amount.

In the arrangement shown in FIGURE 2 sleeve 96 is positioned within cylindrical chamber 9? in relation to the speed of the engine. The shaft 55, driven at a speed proportional to that of the engine, rotates driving member 84 and inner magnet 83 to provide a rotating magnetic field within the space between the magnet 83 and flange 32 for displacing driven member 34 against the tension of spring 96) through an intermediate stud 91. Thus, at any given engine speed, the driven member 84 is displaced in an angular direction proportional to the speed of the engine. The driven member 84 turns shaft 85 and cam 93 to position follower pin 95 in a given position within slot 3'3. The shape of the cam is such that it will impart proportional longitudinal movement to the pin thereby positioning sleeve 96 in relation to engine speed.

Engine lubricating oil under pressure is admitted through inlet 165 for positioning piston 191. Under normal operating conditions the piston 1M is moved to the right, as shown in FIGURE 2, against the resistance of spring 1%7 as the pressure of the lubricating oil increases in response to increased engine speed. This spring is calibrated to move piston 161 in a linear fashion in response to variations of engine speed. When thelubricating oil pressure is above a safe operating value at a given engine speed, the piston 101 is moved to the right in response to the lubricating oil pressure; the sleeve )6 is also moved to the right in response to movement of the pin 95 and the cam )3. However, at this time body portion 193 of piston 191 still extends within sleeve 96 so as to cover opening 114. This prevents the pressurized oil that has been supplied to the bellows 44 from inlet 105 through passages 169 and 111 from draining through sleeve 96 to sump passage 1315.

It canbe seen in this relationship that for any given engine speed sleeve 96 and piston 101 both will be in a given position when the maximum lubricating oilpressure is maintained. Should the lubricating oil pressure fall off at a given speed, piston 101 is moved to the left by spring 107, thus tending to uncover opening 114-. When the oil pressure is reduced below a safe operating pressure for a given speed, piston 101 uncovers opening 114, thus relieving the pressure at bellows 44.

As in the previous arrangement, the orifice 119 in passage 10? performs the function of giving more accurate response when piston 161 has only partially exposed the opening 11 Also, as in the prior arrangement, the collapse of the bellows due to a reduction in pressure actuates a switching arrangement to control the engine or to give an indication to an operator.

This embodiment is adapted to control the safe operating pressure in accordance with the line 222 shown on the graph of FIGURE 6. It will be noted that there is a fixed pressure differential between the maximum lubricating oil pressure and the safe operating pressure for any given engine speed.

Under normal operating conditions, as the speed of the engine increases the sleeve 96 will be moved to the right in response to the rotation of the shaft 55 and the piston 1M will be moved an equal distance to the right in response to the increased lubricating oil pressure. A reduction in the lubricating oil pressure permits movement of the piston 101 to the left throughthe action of linear spring 1637. A given drop in pressure will result in equivalent movement of the piston irrespective of engine speed, and, since the position of sleeve 96 is not affected by lubricating oil pressure, only a drop in the lubricating 9 pressure at a given speed will be effective to cause relative movement between sleeve 96 and piston 101.

Overspeed control is provided in this embodiment by the limiting eflfect of pin 122. As the speed of the engine increases, sleeve 96. will continue to move to the right while piston 161 is also moving to the right. However, when a predetermined point is reached, piston shoulder 1194 will engage the. pin 122 and additional oil pressure increases do not affect the piston 191. Consequently, additional movement of the sleeve to the right as the engine speed continues to increase will uncover opening 114 and relieve the pressure at bellows 44 thereby etfecting actuation of the safety switching mechanism.

The embodiment shown in FIGURES 3 and 4 positions a rod 23 in relation to the pressure output of a centrifugal pump driven at a speed proportional to that of the engine and in response to engine lubricating oil pressure. This configuration applies the engine pressurized lubricating oil to the upper side of diaphragm 21 through a second oil inlet 195, a passage 1% connecting the inlet with the left end of the piston 191, and a passage 152. Instead of acting against a platform 36, as in FIGURE 1, rod 23 positions sleeve 96 through a bell crank 144 so that vertical movement of the rod 23 results in proportional horizontal movement of the sleeve 96. Hence, this sleeve is positioned in relation to the rotational speed of the engine.

As in the embodiment of FIGURE 2, piston 101 is slidably mounted in chamber 97 partially within the sleeve 96 in accord with the lubricating oil pressure being applied against the piston.

Under normal operating conditions the sleeve 96 is moved to the right in proportion to engine speed and the piston 101 is also moved to the right and equivalent distance in response to the lubricating oil pressure. When the lubricating oil pressure falls at a given engine speed,

it affects not only the position of the piston 191, but also the position of the sleeve 96. The linear characteristics of the spring 107 result in a linear movement of the piston 101, whereas the pressure change on the upper side of the diaphragm 21 results in non-linear movement of the rod 23 due to the non-linear characteristics of the spring 27. When the lubricating oil pressure falls at a given speed, the piston 101 tends to move the left while the sleeve 96 tends to move to the right due to the upward movement of the rod 23. When the pressure falls below the safe operating pressure at a given speed, the relative movement of the sleeve and piston is sufiicient to expose the opening 114 to relieve pressure at the previously described bellows 44 shown in FIGURE 6.

As in the embodiment of FIGURE 1, the movement of the rod 23, in response to a drop in the lubricating oil pressure at a given speed, decreases at higher speeds in relation to a similar change at lower speeds and consequently movement of the sleeve 96 to the right decreases at higher speeds when the lubricating oil pressure drops. Thus, the movement of piston 101 must be greater at higher speeds to uncover the opening 114 and'therefore the lubricating oil pressure must fall a greater extent to result in actuation of bellows 44.

It may be desirable to adapt the embodiments of FIG- URES 1, 3 and 4 to eifect engine control when the lubricating oil pressure falls a definite amount at any given engine speed as was accomplished in the embodiment of FIGURE 2. Such a modification is shown in FIG- URE 5, wherein the embodiment of FIGURE 3 and 4 is adapted to such a mode of operation. Pressurized lubricating oil is not applied to the upper side of the diaphragm 21, as in the device of FIGURE 3; instead, a passage 156 to the oil sump is provided. Rod 23 and sleeve 96 are positioned proportional to engine speed by supplying the pressurized output of centrifugal pump 49 to the lower side of diaphragm 21 against the resistive force of a recalibrated non-linear spring 157. This spring 19 must be calibrated to provide non-linear deflection in relation to the non-linear output pressure of the centrifugal pump rather than to the differential between the latter and the lubricating oil pressure, thus providing a linear movement of the rod 23 and the sleeve 96 equal to the linear movement of the piston N1 under normal operating conditions.

Such control may also be effected with the embodiment of FIGURE 1 wherein the supply of pressurized lubrieating oil to the upper side of diaphragm 21 is removed by deleting or restricting passage 39 and recalibrating the non-linear spring 27 as described above with respect to the modification of FIGURES 3 and 4.

As previously mentioned, the modification of FIGURE 5 may be utilized in conjunction with a pump having a linear pressure output to supply pressurized oil to the lower side of diaphragm 21. For such a mode of operation it is necessary to use a linearly calibrated spring 157 in place of the non-linearly calibrated spring to obtain desired movement of rod 23.

From the above discussion it is apparent the types of springs used can be varied to obtain particular results.

Where a pump supplying pressure in accordance with engine speed has nonlinear pressure characteristics a nonlinear type spring can be used to compensate for the pressure differential between the lubricating oil pressure and e the discharge pressure of speed responsive pump 49 that is applied to diaphragm 2 in FIGURE 1 so that the nonlinear characteristics of the spring compensate for the nonlinear pump discharge so that linear movement of rod 23 is obtained. This feature is desirable so that rod 23 may be positioned ata point to reflect only engine speed. In other modifications the type of spring used FIGURE 7, and engine lubricating'oil pressure illustrated by line 220. With particular reference to FIGURES 3 and 5 it should readily be appreciated that springs 27.and 157, respectively, can be matched with springs 107 and 168 along with the pressure supplied by pump 49 to aiford various control margins depending whether a divergent type of pressure differential or a fixed pressure diflterential is desired between the safe lubricating oil and actual lubricating oil pressures. FIGURE 7 illustrates a diverging relationship between engine lubricating oil pressure shown by line 220 and the safe operating oil pressure shown by dotted line 221. Line 222 illustrates a safe operating pressure line which has a fixed differential pressure below engine lubricating oil pressure, line 220.

Many modifications and changes may be made in the details of the above embodiments of our invention; hence,

the scope of our invention is set forth in the appended claims.

We claim:

1. A low oil pressure sensitive device for an internal combustion engine comprising a first control means, a second control means positioned in proportion to engine lubricating oil pressure, an engine driven pump further pressurizing the engine lubricating oil to position said first control means in proportion to engine speed, and means operable in response to the relative position of said first and second control means to indicate when the lubricating oil pressurefalls below a predetermined pressure at any given engine speed.

2. A low oil pressure sensitive device for an internal combustion engine comprising first control means, pressurizing means providing lubricating oil at pressures increasing substantially linearly as the speed of the engine increases under normal operating conditions, an engine driven pump further pressurizing the engine lubricating oil to position said first control means in proportion to engine speed, second control means movable in response to lubricating oil pressure, changes, means responslve to relative movement of both of said first and second control means indicating when the fluid pressure of said pressurizing means falls below a predetermined safe operating pressure at a given engine speed.

3. A low oil pressure sensitive device for an internal combustion engine comprising first supply means supplying lubricating oil at a pressure which increases substantially linearly as the speed of the engine increases, second supply means supplying pressurized oil whose pressure increases in a non-linear manner as the speed of the engine increases, first control means positioned in relation to the pressure differential between said first and second supply means, second control means positioned in relation to the pressure of said first supply means, means responsive to a predetermined relative movement of said first and second control means indicating when the pressure of said first supply means falls below a predetermined safe operating pressure at a given engine speed.

4. A low oil pressure sensitive device for an internal combustion engine comprising a first lubricating oil supply means, the pressure of which increases substantially linearly as the speed of the engine increases; a second pressurized oil supply means, the pressure of which increases as the speed of the engine increases; first control means positioned in proportion to the speed of the engine,

said means including a non-linear spring, a diaphragm 1 adapted to receive pressurized oil from said first supply means on one side and pressurized oil from said second supply means on the other side, said pressure differential serving to move said diaphragm against the resistance of said spring; a second control means positioned in relation to the pressure of said first supply means; and means responsive to a predetermined relative movement of said first and second control means toindicate when the pressure of said first supply means falls below a predetermined pressure at a given enginespeed.

5. A device as set forth in claim 4 wherein said second control means includes a linear spring, and a diaphragm adapted to receive pressurized'oil from said first supply means on one side thereof and to move against the resistance of said linear spring in response to changes in pressure of said first supply means.

6. A device as set forth in claim 4 wherein said second control means includes a linear spring and a piston adapted to receive pressurized oil from said first supply meausso as to move against the resistance of said linear spring in response to changes in pressure of said first supply means.

7. A low oil pressure sensitive device for an internal combustion engine comprising a first supply mean supplying lubricating oil having a pressure varying substantially linearly as engine speed increases, second supply means supplying lubricating oil having a pressure greater than the pressure of said first supply means, said pressure increasing as the speed of the engine increases, first control means movablein response to the pressuredifferential between said first and second supply means, second control means movable in response to the pressure of said first supply means, means responsive to the combined movement of said first and second control means thereby indicating when the pressure of said first supply means falls below a predetermined safe operatingpressure at any given engine speed. I

8. An overspeed indicating device for an internal combustion engine comprising a first control means, a second control means positioned in proportion to the lubricating oil pressure of the engine, means to limit the movement of said second control means when the lubricating oil pressure reaches a predetermined value, an engine driven pump further pressurizing the engine lubricating oilto position said first control means in proportion to engine speed, and means responsive to the relative position of said first and second control means thereby indicating when the speed of the engine increases a predetermined amount above the value at which the movement of the second control means is limited.

9. An overspeed indicating device for an internal combustion engine comprising a first control means, supply means providing pressurized lubricating'oil, the pressure of said oil increasing substantially linearly as the speed oi the engine increases under normal operating conditions, second control means movable in response to pressure changes of said supply means, means to limit the movement of said second control means when the pressure of said supply means reaches a predetermined value, an engine riven pump further pressurizing the engine lubricating oil to position said first control means in proportion to engine speed, and means responsive to the relative position of said first and second control means to indicate when the speed of the engine increases a predetermined amount above the value at which the movement of the second control means is limited.

10. A combination low oil pressure sensitive and overspeed indicating device for an internal combustion engine comprising a first control means, a second control means responsive to engine lubricating oil pressure, means limiting movement of said second control means when a predetermined engine lubricating oil pressure is attained, an engine driven pump further pressurizing the engine lubricating oil to position said first control means in proportion to engine speed, andactuating means responsive to the relative position of said first and second control means to indicate when the lubricating oil pressure falls below a predetermined safe operating value and when the engine speed exceeds a predetermined value.

11. A combination low oil pressure sensitive and overspeed indicating device for an internal combustion engine as described in claim 10 wherein saidmeans limiting movement of said second control means when a predetermined engine lubricating oil pressure is attained results in further relative movement of said first control means until said actuating means is operated.

12. A combination low lubricating oil pressure and overspecd governor device for an internal, combustion engine comprising a first spring biased member operable in response to lubricating oil pressure, a pump to further pressurize the lubricating oil proportional to engine speed, a second spring biased member operable in response to the pressure difierential prevailing between said lubricating oil and the discharge pressure of said pump, an adjustable member adapted to regulate maximum lubricating oil pressures applied to said first spring biased member, and an engine control member sensing lubricating oil pressure and allowing engine operation when both the lubricating ,oil pressure and engine speed are within safe operating limits, said first and second spring biased members moving relative to one another so as to vent said control member to lubricating sump pressure when said safe operating limits are exceeded.

References Cited by the Examiner UNITED STATES PATENTS FRED E. ENGELTHALER, Primary Examiner.

RICHARD B. WILKINSON, Examiner. 

12. A COMBINATION LOW LUBRICATING OIL PRESSURE AND OVERSPEED GOVERNOR DEVICE FOR AN INTERNAL COMBUSTION ENGINE COMPRISING A FIRST SPRING BIASED MEMBER OPERABLE IN RESPONSE TO LUBRICATING OIL PRESSURE, A PUMP TO FURTHER PRESSURIZE THE LUBRICATING OIL PROPORTIONAL TO ENGINE SPEED, A SECOND SPRING BIASED MEMBER OPERABLE IN RESPONSE TO THE PRESSURE DIFFERENTIAL PREVAILING BETWEEN SAID LUBRICATING OIL AND THE DISCHARGE PRESSURE OF SAID PUMP, AN ADJUSTABLE MEMBER ADAPTED TO REGULATE MAXIMUM LUBRICATING OIL PRESSURES APPLIED TO SAID FIRST SPRING BIASED MEMBER, AND AN ENGINE CONTROL MEMBER SENSING LUBRICATING OIL PRESSURE AND ALLOWING ENGINE OPERATION WHEN BOTH THE LUBRICATING OIL PRESSURE AND ENGINE SPEED ARE WITHIN SAFE OPERATING LIMITS, SAID FIRST AND SECOND SPRING BIASED MEMBERS MOVING RELATIVE TO ONE ANOTHER SO AS TO VENT SAID CONTROL MEMBER TO LUBRICATING SUMP PRESSURE WHEN SAID SAFE OPERATING LIMITS ARE EXCEEDED. 